Chemical mechanical polishing slurry, cmp process and electronic device process

ABSTRACT

To provide a slurry for Chemical Mechanical Polishing, a Chemical Mechanical Polishing method using said slurry, and a method of producing electronic devices using said method that makes it possible to achieve a low scratch process capability in processing surfaces such as SiO 2  film surfaces and the like and also to enable speed polishing to attain a high processing efficiency. 
     Slurry for Chemical Mechanical Polishing characterized in comprising abrasive grains and water, wherein said abrasive grains are composite particles coated with ceria particles consisting of organic host particles and ceria particles, zeta potential of said composite particles being a negative potential, the organic host particles constituting the composite particles coated with ceria particles are organic host particles to which carboxyl groups and sulfonyl groups are introduced; the slurry is added with panarization additive; and the planarization additive is poly(methyl)acrylic acid ammonium salt.

FIELD OF THE INVENTION

The invention pertains to the slurry used in the Chemical Mechanical Polishing (“CMP”) process, which is essential to the Shallow Trench Isolation (“STI”) method applied in the producing process of semiconductor devices, the CMP method using said slurry, and the method of producing electronic devices using said method, in particular, said method applied to achieve a low-scratch finish on workpieces being polished and high process efficiency simultaneously, as well as to achieve high planarity on the processed surface of the workpieces.

DESCRIPTION OF THE RELATED ART

Because of a trend in the design of semiconductor devices toward minute and multi-layer structures, the element removal method is making a shift from the LOCOS (Local Oxidation of Silicon) technology, in which the nitride film of the silicon surface is removed by oxidizing a portion of the surface, to the STI technology, which makes higher integration possible. The STI technology is a method of producing electronic devices (semiconductor elements) by first forming a mask of a nitride film on a substrate by patterning, next forming trenches, then forming an interlayer dielectric film consisting of silicon oxide (SiO₂), then removing the surface structure by the Chemical Mechanical Polishing process, and finally removing the residual nitride film. The Chemical Mechanical Polishing (hereinafter called “CMP”) is one of the principal processes of the STI technology and is a great contribution to the process of producing electronic devices (semiconductor elements) and requires not only the process efficiency and the planarity of the surface being processed but also the selectivity of different materials and the cleansing capability and the ease of handling of the slurry. The slurry being used in the CMP typically consists of colloidal silica and fumed silica abrasive grains dispersed in an alkali-based solution and is applied in polishing an object by mechanical polishing by means of silica (SiO₂) and a chemical etching effect, but it has many problems related to the planarity of the surface being processed, scratches, finish point control in polishing, etc. On the other hand, ceria (cerium oxide; CeO₂) abrasive grain is an excellent polishing capability for silicon oxide film, thus eliminating the needs for the edging effect of alkali solution, and has many advantages, e.g., disposability of used slurry, low scratchiness, and no need for strict control of the particle size distribution.

There is a tendency in the process of producing semiconductor devices in recent years that abrasive grains used for the polishing process are becoming increasingly minute while the demand for low scratchiness is intensifying, which in turn is degrading the polishing process efficiency. A method has been proposed for improving such a situation to use compound grains as the polishing grains for the CMP slurry. The intention is to achieve low scratchiness by means of forming compound grains (composite particles coated with inorganic guest particles) by coating organic host particles with fine inorganic grains that cause little scratches, while making it possible to apply a high contact stress at the same time in order to maintain a sufficient polishing speed.

Composite particles coated with inorganic guest particles of the prior art are typically produced by the wet compounding method as disclosed in cited patent document 1. In such a method, the composite particles are produced by causing organic and inorganic particles to adhere with each other electrostatically by controlling the alkalinity pH of an aqueous dispersion containing the organic and inorganic particles in such a way as to cause the zeta potential of the organic particles to have an opposite symbol relative to the that of the inorganic particles.

The abrasive grains produced by this method is electrostatically compounded so that the adhesive strength of the inorganic particles to the organic particles is weak and the inorganic particles tend to drop off easily, thus making it difficult to sustain sufficient polishing speeds. Furthermore, there is also a problem that any additives applied for planarization of the polish-processed surface (hereinafter called “planarization additives”) weaken the electrostatic actions between the particles thus degrading the compounding effect. In the meanwhile, another method has been proposed using a mixture of organic and inorganic particles, but it has a problem that sufficient polishing speeds are not achievable as organic particles are not compounded thus acting as a hindrance factor in polishing.

Typical ceria slurry used in STI-CMP is known to contain planarization additives and aqueous polymer compounds of an anion group are preferred as the planarization additives as they leave little deposits on workpieces, piping, etc. Although the planarization additives provide an advantage that it makes it easier to achieve planarity and uniformity of the workpieces being polished because of the polishing selectivity between the silicon oxide film and the silicon nitride film, which is the polishing stopper filme, it also presents a problem of affecting the polishing speed because the planarization additives work to protect the workpieces from being polished.

There is another method, other than the method of compounding electrostatically, for producing composite particles covered with inorganic guest particles, i.e., a method of providing mechanical energy. This method is to produce composite particles by melting the surface of particles locally and intermittently by applying pressures, shear forces, and friction forces.

The composite particles covered with inorganic guest particles produced by this method have strong adhesive strength between the particles so that the inorganic particles do not fall off by shear forces and contact stress during the polishing.

However, this method has a problem that polish selectivity is completely inactive unless planarization additives are added and that grinding speed drops substantially if planarization additives are added.

Problems to be Solved by the Patent

The present intends to provide slurry for chemical mechanical polishing, a chemical mechanical polishing method using said slurry, and a method of producing electronic devices using said method in order to achieve low scratching on the surface being polished and high process efficiency through realization of high polishing speeds.

Means of Solving the Problems SUMMARY OF THE INVENTION

Slurry for Chemical Mechanical Polishing characterized in comprising abrasive grains (A) and water (B), wherein said abrasive grains (A) are composite particles coated with ceria particles consisting of organic host particles and ceria particles, zeta potential of said composite particles being a negative potential as recited in claim 1.

Slurry for Chemical Mechanical Polishing as recited in claim 1 characterized in said organic host particles constituting said composite particles coated with ceria particles are organic host particles to which carboxyl groups and sulfonyl groups are introduced as recited in claim 2.

Slurry for Chemical Mechanical Polishing characterized in comprising abrasive grains (A) and water (B), wherein said abrasive grains (A) are composite particles coated with ceria particles consisting of ceria particles and poly(methylmethacrylate) particles to which carboxyl groups are introduced as recited in claim 3.

Slurry for Chemical Mechanical Polishing as recited in claim 3 characterized in said abrasive particles (A) being composite particles coated with ceria particles having a surface layer produced by fusion locally and intermittently applying pressure and shear force to mixed fine particles consisting of ceria particles and poly(methylmethacrylate) particles to which carboxyl groups are introduced as cited in claim 4 as recited in claim 4.

Slurry for Chemical Mechanical Polishing as recited in claim 3 characterized in the concentration of said abrasive particles (A) relative to said water (B) being in ratios of 0.2 to 10 weight percentage as recited in claim 5.

Slurry for Chemical Mechanical Polishing as recited in claim 3 characterized in said abrasive particles (A) being composite particles having average particles diameters of 0.3 to 10 μm as recited in claim 6.

Slurry for Chemical Mechanical Polishing comprising abrasive grains (A), water (B) and a planarization additive (C) characterized in said abrasive grains (A) being composite particles coated with ceria particles consisting of organic host particles and ceria particles, while zeta potential of said composite particles being a negative potential as recited in claim 7.

Slurry for Chemical Mechanical Polishing as recited in claim 7 characterized in said organic host particles constituting said composite particles coated with ceria particles being organic host particles to which carboxyl groups and sulfonyl groups are introduced as recited in claim 8.

Slurry for Chemical Mechanical Polishing comprising abrasive grains (A), water (B) and a planarization additive (C) characterized in said abrasive grains (A) being composite particles coated with ceria particles consisting of ceria particles and poly(methylmethacrylate) particles to which carboxyl groups are introduced as recited in claim 9.

Slurry for Chemical Mechanical Polishing as recited in claim 9 characterized in said composite particles coated with ceria particles being composite particles coated with ceria particles having a surface layer produced by fusion locally and intermittently applying pressure and shear force to mixed fine particles consisting of ceria particles and poly(methylmethacrylate) particles to which carboxyl groups are introduced as cited in claim 10.

Slurry for Chemical Mechanical Polishing as recited in claim 9 characterized in the concentration of said abrasive particles (A) relative to said water (B) being in ratios of 0.2 to 10 weight percentage as recited in claim 11.

Slurry for Chemical Mechanical Polishing as recited in claim 9 characterized in said abrasive particles (A) being composite particles having average particles diameters of 0.3 to 10 μm as recited in claim 12.

Slurry for Chemical Mechanical Polishing as recited in claim 9 characterized in the concentration of said planarization additive (C) relative to said water (B) being in ratios of 0.05 to 5 weight percentage as recited in claim 13.

Slurry for Chemical Mechanical Polishing as recited in claim 9 characterized in said planarization additive (C) being poly(methyl)acrylic acid ammonium salt as recited in claim 14.

A Chemical Mechanical Polishing method using slurry for Chemical Mechanical Polishing comprising abrasive grains (A) and water (B) characterized in said abrasive grains (A) being composite particles coated with ceria particles consisting of organic host particles and ceria particles, and causing a workpiece to be polished by being in contact with the slurry for Chemical Mechanical Polishing comprising composite particles, wherein zeta potential of said composite particles being a negative potential as recited in claim 15.

A Chemical Mechanical Polishing method as recited in claim 15 characterized in causing a workpiece to be polished by being in contact with the slurry for Chemical Mechanical Polishing, wherein said organic host particles constituting said composite particles coated with ceria particles being organic host composite particles to which carboxyl groups and sulfonyl groups are introduced as recited in claim 16.

A Chemical Mechanical Polishing method characterized in causing a workpiece to be in contact with and polished by slurry for Chemical Mechanical Polishing, said slurry for Chemical Mechanical Polishing comprising abrasive grains (A) and water (B), wherein said abrasive grains (A) being composite particles coated with ceria particles consisting of ceria particles and poly(methylmethacrylate) particles to which carboxyl groups are introduced as recited in claim 17.

A Chemical Mechanical Polishing method using slurry for Chemical Mechanical Polishing comprising abrasive grains (A), water (B) and planarization additives (C) characterized in said abrasive grains (A) being composite particles coated with ceria particles consisting of organic host particles and ceria particles, wherein zeta potential of said composite particles being a negative potential as recited in claim 18.

A Chemical Mechanical Polishing method as recited in claim 18 characterized in causing a workpiece to be polished by being in contact with the slurry for Chemical Mechanical Polishing, wherein said organic host particles constituting said composite particles coated with ceria particles being organic host composite particles to which carboxyl groups and sulfonyl groups are introduced as recited in claim 19.

A Chemical Mechanical Polishing method characterized in causing a workpiece to be polished by being in contact with slurry for Chemical Mechanical Polishing comprising abrasive grains (A), water (B) and planarization additives (C), wherein said abrasive grains (A) are composite particles coated with ceria particles consisting of ceria particles and poly(methylmethacrylate) particles to which carboxyl groups are introduced as recited in claim 20.

A method of producing an electronic device characterized in including a process of causing a workpiece to be polished by being in contact with slurry for Chemical Mechanical Polishing comprising abrasive grains (A) and water (B), wherein said abrasive grains (A) being composite particles coated with ceria particles consisting of organic host particles and ceria particles, and zeta potential of said composite particles being a negative potential as recited in claim 21.

A method of producing an electronic device as recited in claim 21 characterized in including a process of causing a workpiece to be polished by being in contact with slurry for Chemical Mechanical Polishing, wherein said organic host particles constituting said composite particles coated with ceria particles being organic host composite particles to which carboxyl groups and sulfonyl groups are introduced as recited in claim 22.

A method of producing an electronic device characterized in including a process of causing a workpiece to be polished by being in contact with slurry for Chemical Mechanical Polishing comprising abrasive grains (A) and water (B), wherein said abrasive grains (A) are composite particles coated with ceria particles consisting of ceria particles and poly(methylmethacrylate) particles to which carboxyl groups are introduced as recited in claim 23.

A method of producing an electronic device characterized in including a process of causing a workpiece to be polished by being in contact with slurry for Chemical Mechanical Polishing abrasive grains (A), water (B) and planarization additives (C) characterized in said abrasive grains (A) being composite particles coated with ceria particles consisting of organic host particles and ceria particles, while zeta potential of said composite particles being a negative potential as recited in claim 24.

A method of producing an electronic device as recited in claim 24 characterized in including a process of causing a workpiece to be polished by being in contact with slurry for Chemical Mechanical Polishing, wherein said organic host particles constituting said composite particles coated with ceria particles being organic host composite particles to which carboxyl groups and sulfonyl groups are introduced as recited in claim 25.

A method of producing an electronic device characterized in causing a workpiece to be polished by being in contact with slurry for Chemical Mechanical Polishing comprising abrasive grains (A), water (B) and planarization additives (C), wherein said abrasive grains (A) are composite particles coated with ceria particles consisting of ceria particles and poly(methylmethacrylate) particles to which carboxyl groups are introduced as recited in claim 26.

The organic host particles that constitute the composite particles of the abrasive grains (A) of the present invention can be poly(methylmethacrylate) (“PMMA”) particles to which carboxyl groups or sulfonyl groups are introduced in order to make their zeta potential a negative potential, polystyrene particles, or their copolymer particles. Moreover, the organic host particles of the present invention are preferably crosslinked particles, since they need to have heat-resistant temperatures and hardness to some degrees. Therefore, it is preferable that they are mono-dispersion particles produced by methods such as soap-free emulsion polymerization and dispersion polymerization methods. The particle diameters of organic host particles are required to be within 0.3 to 10 μm. The reason is that they have problems such as polishing speeds dropping substantially because they have difficulties in compounding with inorganic guest particles if the organic host particles' diameters fail to reach 0.3 μm, while there is a problem of being unable to supply slurry with a uniform particle concentration on the polishing surface because of a poor slurry distribution condition if the organic host particles' diameters exceed 10 μm. The organic host particles' diameters are preferably within 1-7 μm.

While the inorganic particles constituting the composite particles that are used as the abrasive grains of the present invention can be either cerium oxide (CeO₂), manganese sesquioxide (Mn₂O₃) or cerium hydroxide (Ce(OH)₄), the abrasive grains made of ceria particles, i.e., cerium oxide, have advantages that they have an excellent polishing capability against the silicon oxide film and that it is easy to achieve the sufficient polishing selectivity (polishing speed ratio of SiO₂/Si₃N₄) between the silicon oxide film and the silicon nitride (Si₃N₄), which is used as the stopper film in the STI-CMP process, with the use of the planarization additives. The average particle diameter of the inorganic guest particles of the present invention is preferably within the range of 10-500 nm. The reason is that it causes a problem that the polishing speed drops if the average diameter the inorganic guest particles is less than 10 nm and a problem that the scratches on the workpiece increase if the average diameter of the inorganic guest particles exceeds 500 nm. While inorganic particles are generally produced by either the chemical vapor deposition method or the wet process, the inorganic particles of the present invention are preferably produced by the chemical vapor deposition method considering the productivity as the composite particles of the present invention are produced by the dry complex method. Moreover, since the higher the surface coverage ratio of the organic host particles by the inorganic particles, the higher the speed of polishing can be, the surface coverage ratio should preferably be higher than 20%.

In the slurry for Chemical Mechanical Polishing of the present invention consisting of the composite particles used as the abrasive grains (A) and water (B), the concentration of said composite particles (abrasive grains) relative to water (B) is 0.2-10 weight percentage. The reason is that there is a problem that a sufficient polishing speed cannot be achieved if said value is less than 0.2 weight percentage, and there is another problem that it results in a very poor dispersion of the slurry if it exceeds 10 weight percentage. Said value should more preferably be 0.5-5 weight percentage.

The planarization additives (C) of the present invention are not particularly restricted so long as the slurry for CMP can adhere to the inorganic dielectric film when the slurry for CMP is in contact with the inorganic dielectric film of the workpiece, for example, water soluble polymers and surface-active agents are used preferably, but more preferably, those that adhere to silicon oxide and silicon nitride films when they contact with those films but separate from those films as the polishing pressure increases. The examples of those planarization additives (C) are chemical compounds such as poly(methyl)acrylic acid, poly(methyl)acrylic acid derivative, poly(methyl)acrylic acid ammonium salt, polyvinyl pyrolidone, polyvinyl acetal, polyvinyl formal, polyvinyl butyral, polyvinyl pyrolidone-iodine derivative, polyvinyl(5-methyl-2-pyrolidinone), polyvinyl(2-piperidinone), polyvinyl(3,3,5-trimethyl-2-pyrolidinone), poly(N-vinyl carbazole), poly(N-alkyl-vinyl carbazole), poly(N-alkyl-3-vinyl carbazole), poly(N-alkyl-4-vinyl carbazole), poly(N-vinyl-3,6-dibromocarbazole), polyvinyl phenylketone, polyvinyl acetphenone, poly(4-vinyl pyridine), poly(4-β-hydoxyethyl pyridine), poly(2-vinyl pyridine), poly(2-β-vinyl pyridine), poly(4-vinyl pyridine), poly(4-hydroxyethyl pyridine), poly(4-vinyl pyridinium salt), poly(α-methylstyrene-co-4-vinyl pydinium hydrochloride), poly(1-(3-sulfonyl)-2-vinyl pydinium petain-co-p-potassium styrenesulfonate), poly(N-vinylimidazole), poly(4-vinylimidazole), poly(5-vinylimidazole), poly(1-vinyl-4-methyl oxazolidinone), polyvinyl acetoamide, polyvinylmethyl acetoamide, polyvinylethyl acetoamide, polyvinylphenyl acetoamide, polyvinylmethyl propionamide, polyvinylethyl propionamide, polyvinylmethyl isobutylamide, polyvinylmethylbenzyl amide, polyvinyl alcohol, polyvinyl alcohol derivative, polyacrolein, polyacronitrile, polyvinyl acetate, poly(vinyl acetate-co-methyl methacryliate), poly(vinyl acetate-co-pyrolidin), poly(vinyl acetate-co-acetonitrile), poly(vinyl acetate-co-N, N-diarylcyanide), poly(vinyl acetate-co-N,N-diarylamine), and poly(vinyl acetate-co-ethylene).

The planarization additives with average molecular weight of 500 or more are preferable, with no upper limit, but those with average molecular weight of one million or less are more preferable from the solubility standpoint. The surface-active agents can be nonionic surface-active agents and anionic surface-active agents, but those having no alkali metals are more preferred. Of these surface-active agents, either one of polyethylene glycol type anion type surface-active agents, glycol group, glycerin fatty acid ester, sorbit fatty acid ester, fatty acid alkanol amide, alcohol sulfuric acid ester salt, alkyl ether sulfuric acid ester salt, alkyl benzene sulfonate, or alkyl phosphoric ester is preferable. The amount of the planarization additives to be added should preferably be 0.05-5 weight percentage relative to 100 weight percentage of the CMP slurry. The reason is that the additive effect may not be achieved if the amount of the planarization additives is less than said range, while the polishing speed may reduce if it is more than the range.

The CMP slurry of the present invention may be added with dispersion additives and pH adjusting agents. Said dispersion agents must be selected in accordance with inorganic particles constituting organic particles; for example, if cerium oxide is used as the inorganic particle, polyacryl acid ammonium salt and polymer dispersion agents containing acryl acid ammonium salt as a copolymer ingredient are preferable. Other preferable dispersion agents include triethanol amine lauril sulfate, ammonium lauril sulfate, triethanol amine polyoxyethylene alkylether sulfate, special polycarbonic acid type polymer, polyoxyethelne lauril ether, polyoxyethelne cetyl ether, polyoxyethelne stearylether, polyoxyethelne oleyl ether, polyoxyethelne higher alochol ether, polyoxyethelne octylphenyl ether, polyoxyethelne nonylphenyl ether, polyoxyalkylene alkyl ether, polyoxy ethylene derivative, polyoxy ethelene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan mono-oleate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbit tetraoleinate, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, polyethylene glycol mono-oleate, polyoxyethylene alkylamine, polyoxyethylene hydrogenated castor oil, alkyl alkanol amide, polyvinyl pyrolidone, coconut amine acetate, stearyl amine acetate, lauril petine, stearil petine, lauril dimethylamine oxide, and 2-alkyl-N-carboxymethyl-N-carboxymethyl-N-hydroxyethyl imidazorlnium petine.

The amount of the abovementioned additives in reference to the relations with the dispersion characteristics and prevention of precipitation of the particles in the CPM slurry as well as with the polishing damages should be within 0.01-2.0 weight parts relative to 100 weight parts of cerium particles (oxide cerium particles). The molecular weight of the abovementioned dispersion agents should preferable be within the rand of 100-50,000, more preferably 1,000-10,000. The reason is that it may not able to achieve a sufficient polishing speed in polishing silicon oxide film or silicon nitride film if the molecular weight of the dispersion agent is less than 100, while the viscosity becomes too high and the storage stability of the CMP slurry drops if the molecular weight of the dispersion agent exceeds 50,000.

The slurry for Chemical Mechanical Polishing (CMP) according to the present invention is capable of sustaining high polishing speeds and providing a sufficient polishing selectivity for achieving the planarity of the surface being processed even if the planarization additives (C) are not added by using the composite particles with a negative zeta potential as the abrasive particles. While the polishing speed drops substantially if the zeta potential of the composite particles, i.e., abrasive grains, is a positive potential, as it causes excessive adherence of planarization additives (C) even though the planarization additives are added, the slurry for CMP according to the present invention makes it possible to suppress the adherence of the planarization additives (C), thus achieving both a high polishing speed and a sufficient polish selectivity by means of using the composite particles with a negative zeta potential as the abrasive grains.

The method of producing electronic devices using the slurry for CMP consisting of abrasive grains (A) and water (B), the CMP method using said slurry, and the method of producing electronic devices using said method all according to the present invention achieve low scratch characteristics on the surface being polished in the CMP process and a high process efficiency due to a high speed polishing process as a result of using the composite particles coated with ceria particles consisting of organic host particles and ceria particles as said abrasive grains (A), wherein the zeta potential of said composite particles is a negative potential.

In addition to the above effect, the method of producing electronic devices using the slurry for CMP, the CMP method using said slurry, and the method of producing electronic devices using said method according to the present invention provide an effect of achieving the planarity of the surface being polished as well by adding the planarization additives (C) to said slurry for CMP.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the present invention will be described in the following, but the present invention should not be construed to be limited to the present embodiment. Examples of the method of producing dry type composite particles comprising organic host particles and inorganic guest particles can be found in the compounding methods according to the Mechanofusion System of Hosokawa Micron Co., Ltd. and the Hybridizing System of Nara Machinery Co., Ltd. These compounding methods are intended to produce composite particles by combining different ingredient particles on molecular levels mechanochemically by applying frictions, pressures and shear forces based on mechanical energy. These methods are simpler in the processes than the method of producing wet type composite particles and have higher degrees of freedom of combination.

Next, the polishing test method conducted to prove the operating effect of the present embodiment of the invention. A polishing device by Engis Corporation, IMRTECH 10DVT, was used to measure the polishing speed on the silicon oxide (SiO₂) film by gluing a polishing pad (IC1000/Suba 400 by Nitta Haas Inc.) on top of a polishing platen (diameter: 200 mm) and another pad on the bottom of a guide ring. A silicon oxide wafer, which was the material to be polished, was set on the bottom of the polishing weight which was then placed on the polishing pad inside the guide ring, allowing the guide ring and the polishing weight to rotate in the same direction as that of the platen by the friction resistance of the contract surface in accordance with the rotation of the platen thus to create polishing of the material The polishing load was adjusted by the number of polishing weights, while setting the weight to 30 kPa, the rotating speed of the platen to 150 rev/minute, and the polishing time to 2 minutes. During the polishing, the slurry was supplied continuously by dropping (15 ml/min) by means of a tube pump. The silicon oxide film wafer was cleaned by ultrasonic cleaning for 10 minutes after the polishing using pure water and then dried. The film thickness of the silicon oxide film was measured using an optical interferometer type film thickness measuring deice to obtain the difference in the film thickness before and after the polishing in order to calculate the polishing speed.

Embodiments Embodiments 1-3

In all of the embodiments 1-3 according to the present invention, the slurry for CMP was based on composite particle abrasive grains produced by the dry type composite producing method compounding organic host particles of poly(methylmethacrylate) (PMMA) mono-dispersion particles (5 μm) with inorganic particles of ceria (CeO₂) particles (14 nm) in such a way that the zeta potential becomes a negative potential. Since it is difficult to measure the zeta potentials of the composite particle abrasive grains thus produced as the high concentration slurry, large-sized particles and composite particles cannot be measured easily by the conventional laser Doppler method, it was measured by Matec Applied Sciences' instrument, ESA-9800, that measures the zeta potential by measuring the pressure amplitude of the high frequency vibrations caused by electrophoresis. The zeta potentials of the composite particles were −40 mV in embodiment 1, −20 mV in embodiment 2, and −5 mV in embodiment 3. The slurries of these embodiments had composite particles with negative potentials as a result of adjusting the zeta potentials by means of changing the concentrations introducing carboxyl groups to the organic host particles. The above polishing tests were conducted by adjusting the concentration of abrasive grains (weight ratio of the abrasive grains relative to water) to 1 weight percentage. In order to check the polishing selectivity, a Si₃N₄ film wafer was used as the polish stopper film in addition to the SiO₂ wafer as the workpiece to be polished. The polishing speed and the polishing selectivity (ratio of polishing speeds of the SiO₂ film and the Si₃N₄ film) were evaluated.

Comparative examples 1 and 2 were based on composite particles consisting of conventional poly(methylmethacrylate) (“PMMA”) mono-dispersion particles and PMMA mono-dispersion particles to which hydroxyl groups were introduced in order to achieve composite particles of positive potential. Example 3 is the sample for polishing speed comparison prepared by using inorganic host particles consisting of nano ceria alone.

Table 1 shows the evaluation results of CMP slurries of embodiments 1 to 3 and comparative examples 1 to 3.

TABLE 1 Composite particle Particle abrasive diameter grains of Polishing Inor- composite Grain Zeta Polishing selectivity 0anic Organic particles concentration potential speed (SiO₂/ particles particles (μm) (wt %) (mV) (nm/min) Si₃N₄) Embodiment 1 CeO₂ PMMA 5 1.0 −40 60 25 2 CeO₂ PMMA 5 1.0 −20 90 20 3 CeO₂ PMMA 5 1.0 −5 110 15 Comparative 1 CeO₂ PMMA 5 1.0 20 120 4 example 2 CeO₂ PMMA 5 1.0 60 125 3 3 CeO₂ only — 1.0 — 20 3

As shown in table 1, the slurries for CMP of embodies 1 through 3 showed much faster SiO₂ polishing speeds compared to that of comparative example 3 using nano ceria alone, indicating excellent polishing capabilities, also indicating that better polishing selectivity was achieved when the absolute value of the negative potential of the zeta potentials of the composite particles increased. Since their zeta potentials were positive in comparative examples 1 and 2, adequate polishing selectivity was not achieved in both cases although the polishing speeds were very high.

Although PMMA particles implanted with carboxyl groups were used as the organic host particles in embodiments 1 through 3 in order to make the zeta potential of the composite particles negative, organic host particles having functional groups implanted with sulfonyl groups or other functional groups that cause a negative potential can be used as well. Although PMMA particles were used as the base material for the organic host particles in embodiments 1 through 3, we note here that similar effects can be achieved by using polystyrene particles implanted with functional groups as the organic host particles. While the aforementioned dry type composite particles were used in embodiments 1-3, it was learned that it is also possible to achieve high speed polishing and sufficient polishing selectivity using wed type composite particles produced by hetero aggregation. Although it is written in this specification that the abrasive grains used in the embodiments are totally made up of composite particles alone for the simplicity sake, some nano ceria particles that are not compounded exist in those particles in reality, as they are not 100% compounded in the dry type composite particle producing method. If the surface coverage rate of the composite particles is the same, the more uncompounded nano ceria particles exist, the faster the polishing speed of the SiO₂ film. Thus, the same effect can be achieved in the slurry using abrasive grains where the composite particles are added with nano ceria. Although HDP-TEOS (High Density Plasma-Tetra Ethoxy Silane that is capable of lowering the softening temperature and achieving gettering action as the SIO₂ film, which is the workpiece to be polished in these embodiments, thermally oxidizing films and silicon oxide films such as 03-TEOS and SOG (Spin On Glass).

Embodiments 4-7

Next, the relation between the concentration of the abrasive grains of composite particles and the polishing speed in the slurry for CMP was evaluated. The polishing test was conducted under similar conditions as in embodiments 1 through 3. The slurry for CMP used in embodiments 4 through 7 were composite particle abrasive grains consisting of mono-dispersion particles (5 μm) as the organic host particles of PMMA and CeO₂ particles (14 nm) as the inorganic guest particles same as in embodiment 2, having the zeta potential of −20 mV. The concentration of the abrasive grains relative to water was 0.2 wt % in embodiment 4, 1.5 wt % in embodiment 5, 5 wt % in embodiment 6, and 10 wt % in embodiment 7.

While the abrasive grains of composite particles used in embodiment 2 were used both for comparative examples 4 and 5, the concentration of the abrasive grains relative to water was 0.1 wt % in embodiment 4, and 20 wt % in embodiment 5 in the polishing tests conducted similarly to embodiments 1 through 3. Table 2 shows the evaluation results of embodiments 4 through 7 as well as comparative examples 4 and 5.

TABLE 2 Composite Particle particle diameter abrasive of Grain grains composite concen- Polishing Inorganic Organic particles tration speed particles particles (μm) (wt %) (nm/min) Embodiment 4 CeO₂ PMMA 5 0.2 60 5 CeO₂ PMMA 5 1.0 90 6 CeO₂ PMMA 5 5 140 7 CeO₂ PMMA 5 10 150 Comparative 4 CeO₂ PMMA 5 0.1 10 example 5 CeO₂ PMMA 5 20 150

As can be seen from Table 2, the slurries of embodiments 4 through 7 showed very high SiO₂ film polishing speeds and excellent polishing capabilities in comparison with comparative example 4. In contrast to this, comparative example 4 with the abrasive grain concentration of 0.1 wt % showed a much slower polishing speed and sufficient polishing speeds for practical use could not be achieved. Comparative example 5 with the abrasive grain concentration of 20 wt % showed almost no difference and was in a saturated condition even in comparison with embodiment 7 with the abrasive grain concentration of 10 wt %. Furthermore, the dispersion state of the abrasive grains of comparative example 5 was very poor although it is not shown in the table.

Embodiments 8-11

Next, the relation between the concentration of the abrasive grains of composite particles and the polishing speed in the slurry for CMP was evaluated. The polishing test was conducted under the same conditions. The slurries for CMP used in embodiments 8 through 11 were composite particle abrasive grains consisting of organic host particles of PMMA mono-dispersion particles and inorganic guest particles of CeO₂ particles (14 nm), having the abrasive concentration of 1 wt %, while the average particle size of the PMMA mono-dispersion particles used as organic host particles was 0.3 μm in embodiment 8, 1.5 μm in embodiment 9, 5 μm in embodiment 10, and 10 μm in embodiment 11. Since the average particle diameter of the inorganic guest particles was 14 nm, sufficiently smaller than that of the host particles, so that the average particle diameter of the abovementioned PMMA mono-dispersion particles can be regarded as the average particle diameter of the composite particles, which were the abrasive grains. Since carboxyl groups were introduced into PMMA, the zeta potentials of all the composite particles thus produced were negative potentials. In addition to the polishing speed, the damages of the wafers after polishing were observed.

Comparative examples 6 and 7 were identical to embodiments 8 through 11 in that they were based pm composite particle abrasive grains consisting of PMMA mono-dispersion particles used as the organic host particles and CeO₂ particles (14 nm) as the inorganic guest particles, with the concentration of the abrasive grains of 1 wt % and the zeta potential of the abrasive particles of a negative potential, except that the particle diameter mono-dispersant PMMA particles of the organic host particles, which is essentially equal to that of the composite particles, was 0.15 μm in comparative example 6 and 20 μm in comparative example 7.

Table 3 shows the evaluation results of embodiments 8 through 11 and comparative examples 6 and 7, which were conducted in a similar manner as the previous polishing test method.

TABLE 3 Composite particle Particle abrasive diameter of particles composite Grain Polishing Inorganic Organic particles concentration speed Damages particles particles (μm) (wt %) (nm/min) observed Embodiment 8 CeO₂ PMMA 0.3 1.0 80 No 9 CeO₂ PMMA 1.5 1.0 150 No 10 CeO₂ PMMA 5 1.0 90 No 11 CeO₂ PMMA 10 1.0 70 No Comparative 6 CeO₂ PMMA 0.15 1.0 30 No example 7 CeO₂ PMMA 20 1.0 60 Yes

As shown in Table 3, the slurries for CMP in embodiments 8-11 showed very fast SiO₂ polishing speed, no damages on wafers after polish, and excellent performances overall. The fasted polishing speed was noted in embodiment 9 where the average diameter of the composite particles was 1.5 μm. In contrast to that, the polishing speed dropped substantially and sufficient polishing speeds could not be achieved in comparative example 6 where the average particle diameter of the composite particles was 0.15 μm. Furthermore, although a sufficient polishing speed was achieved, many damages were observed on the polished surface, and the slurry dispersion state was very poor in comparative example 7 where the average particle diameter of the composite particles was 20 μm. In the dry composite particle producing method, it is not easy to produce composite particles if the average particle diameter of the organic host particles is less than 1 μm, so that it should preferably be 1-7 μm. The average particle diameter of the composite particle abrasive grains relates very much to the type of the polishing pad, especially to the pattern of the polishing pad which is made of porous urethane plastic and its surface roughness, so that it is mandatory to select the particle diameter suited for the polishing pad to be used.

Embodiments 12-14

The slurries for CMP added with planarization additives are evaluated here. Embodiments 12 through 14 were based on the slurries for CMP used in embodiments 1 through 3 added with poly(methyl)acrylic acid ammonium salt as an planarization additive. The composition of the additive relative to water was 0.3 wt %, the pH value of the slurries was adjusted to 5 using ammonia, the abrasive grain concentration relative to water was 1.0 wt %, and the zeta potential prior to the addition of the planarization additive was −40 mV in embodiment 12, −20 mV in embodiment 13, and −5 mV in embodiment 14.

Comparative examples 8 through 10 were based on the slurries used in comparative embodiments 1 through 3 added with poly(methyl)acrylic acid ammonium salt as an planarization additive. The composition of the additive relative to water was 0.3 wt %, the pH value of the slurries was adjusted to 5 using ammonia, and the abrasive grain concentration relative to water was 10 wt %.

Table 4 shows the evaluation results of embodiments 12 through 14 and comparative examples 8 through 10, which were conducted in a similar manner as the previous polishing test method.

TABLE 4 Composite Particle particle Diameter abrasive of Polishing Polishing grains composite Grain Zeta Planarization speed selectivity Inorganic Organic particles concentration potential additive (nm/ (SiO₂/ particles particles (μm) (wt %) (mV) (wt %) min) Si₃N₄) Embodiment 12 CeO₂ PMMA 5 1.0 −40 0.3 55 45 13 CeO₂ PMMA 5 1.0 −20 0.3 65 40 14 CeO₂ PMMA 5 1.0 −5 0.3 80 35 Comparative 8 CeO₂ PMMA 5 1.0 20 0.3 5 24 example 9 CeO₂ PMMA 5 1.0 60 0.3 5 23 10 CeO₂ only — 1.0 0.3 5 23

As can be seen from Table 4, the slurries of embodiments 12 through 14 showed very high SiO₂ film polishing speeds and excellent polishing capabilities in comparison with comparative example 10 with nano ceria only. Moreover, comparative examples 8 and 9 used composite particles with positive zeta potentials showed substantial drops in the polishing speeds as a result of adding planarization additives which work to prevent polishing. In contrast to that, the slurries for CMV of embodiments 12 through 14 using composite particles with negative zeta potentials caused only small polishing speed reductions even though planarization additives are added, and could sustain adequate polishing selectivity as well.

Although PMMA particles implanted with carboxyl groups were used as the organic host particles in embodiments 12 through 14 in order to make the zeta potential of the composite particles negative, organic host particles having functional groups implanted with sulfonyl groups or other functional groups that cause a negative potential can be used as well. Although PMMA particles were used as the base material for the organic host particles in embodiments 12 through 14, we note here that similar effects can be achieved by using polystyrene particles implanted with functional groups as the organic host particles. Embodiments 12 through 14 used slurries added with planarization additives with the pH value of 5, it was observed that similar results as in embodiments 12 through 14 can be achieved if the pH value is within 4-8. The planarization additives used in the present invention are not limited to poly(methyl)acrylic acid ammonium salt, but rather can be any kind of additives that adhere to inorganic dielectric films placed as workpieces to be polished such as SiO₂ and Si₃N₄ and separate when polishing surface pressure increases, when they are incorporated as additives.

Embodiments 15-18

Next, the relation between the concentration of the abrasive grains of composite particles added with planarization additives and the polishing speed in the slurry for CMP was evaluated. The slurry for CMP used in embodiments 15 through 18 was made from composite particle abrasive grains consisting of PMMA mono-dispersion particles (5 μm) as the organic host particles and CeO₂ particles (14 nm) as the inorganic guest particles same as in embodiments 2 and 13, the zeta potential was −20 mV, and poly(methyl)acrylic acid ammonium salt was used as the planarization additive. The composition of the additive relative to water was 0.3 wt %, the pH value of the slurry was adjusted to 5 using ammonia, the concentration of the abrasive grains relative to water was 0.2 wt % in embodiment 15, 1.0 wt % in embodiment 16, 5 wt % in embodiment 17, and 10 wt % in embodiment 18.

The aforementioned abrasive grains of composite particles used in embodiments 2 and 13 were also used in comparative examples 11 and 12, and the concentration of the abrasive grains relative to water was 0.1 wt % in comparative example 11 and 20 wt % in comparative example 12.

Table 5 shows the evaluation results of embodiments 15 through 18 and comparative examples 11 and 12, which were conducted in a similar manner as the previous polishing test method.

TABLE 5 Composite particle Particle abrasive diameter Concentration grains of composite Grain of Polishing Inorganic Organic particles concentration planarization speed particles particles (μm) (wt %) additive (nm/min) Embodiment 15 CeO₂ PMMA 5 0.2 0.3 40 16 CeO₂ PMMA 5 1.0 0.3 65 17 CeO₂ PMMA 5 5 0.3 110 18 CeO₂ PMMA 5 10 0.3 120 Comparative 11 CeO₂ PMMA 5 0.1 0.3 5 example 12 CeO₂ PMMA 5 20 0.3 120

As can be seen from Table 5, the slurries of embodiments 15 through 18 showed very high SiO₂ polishing speeds and excellent polishing capabilities in comparison with comparative example 11. When the concentration of the abrasive grains was less than 0.2 wt %, the polishing speed dropped sharply and sufficient speeds for practical use could not be achieved as shown in comparative example 11. On the other hand, when the abrasive concentration was as much as 20 wt % as shown in comparative example 12, no difference in the polishing speed was observed even in comparison with comparative example 18 whose grain concentration was 10 wt % and the polishing speed was almost saturated. Furthermore, in comparative example 12 with the concentration of the abrasive grains of 20 wt %, the dispersion state of the abrasive grains was very poor although it does not appear on the table. Moreover, according to the evaluation of the effect of the average particle diameter of the composite particles concerning the slurries added with the planarization additives, the polishing speed dropped substantially and sufficient polishing speed for practical use could not be achieved when the average particle size of the composite particle abrasive grains was less than 0.3 μm. Also, when the average particle diameter of the composite particle abrasive grains was 20 μm, many damages were noted on the workpiece surface and the dispersion state was very poor although the polishing speed was sufficiently high. From these results, it was learned that the average particle diameter of the composite particle abrasive grains should preferably be within the range of 0.3-10 μm, and that it is preferable to select slurries for CMP using abrasive grains of composite particles of the optimum particle diameter that matches the type of polishing pad, in particular, the pattern and surface roughness of polishing pads made of porous urethane plastics.

Embodiments 19-22

Next, the relation between the concentration of planarization additive and polishing selectivity of the slurry for CMP was evaluated. In order to check the polishing selectivity, the SiO₂ film wafer was chosen as the workpiece to be polished and the Si₃N₄ film wafer was chosen as the polishing stopper film. The slurry for CMP used in embodiments 19-22 was made from composite particle abrasive grains used in embodiment 13 consisting of PMMA mono-dispersion particles (5 μm) as the organic host particles and CeO₂ particles (14 nm) as the inorganic guest particles, wherein the zeta potential was −20 mV, the concentration of the abrasive grains relative to water was 1.0 wt %, poly(methyl)acrylic acid ammonium salt was used as an planarization additive, and the pH value of the slurry was adjusted to 5 using ammonia. The concentration of the planarization additive, i.e., poly(methyl)acrylic acid ammonium salt, relative to water was 0.05 wt % in embodiment 19, 0.3 wt % in embodiment 20, 1.0 wt % in embodiment 21, and 5.0 wt % in embodiment 22.

The composite particle abrasive grains having the same planarization additive concentration as that of embodiments 19 through 22 were used in comparative examples 13 and 14, wherein the concentration of the abrasive grains relative to water was 1.0 wt %, the concentration of poly(methyl)acrylic acid ammonium salt used as the planarization additive was 0.001 wt % in comparative example 13 and 10 wt % in comparative embodiment 14, and the slurry's pH values was adjusted to 5 using ammonia.

Tests were conducted under the same condition of the aforementioned polishing test method for embodiments 19 through 22 and comparative examples 13 and 14 in order to check the operating effects of the embodiments. Table 6 shows the results of the tests.

TABLE 6 Composite Particle particle diameter abrasive of Polishing grains composite Grain Planarization Polishing selectivity Inorganic Organic particles concentration additive speed (SiO₂/ particles particles (μm) (wt %) (wt %) (nm/min) Si₃N₄) Embodiment 19 CeO₂ PMMA 5 1.0 0.05 85 20 20 CeO₂ PMMA 5 1.0 0.3 65 40 21 CeO₂ PMMA 5 1.0 1.0 40 50 22 CeO₂ PMMA 5 1.0 5.0 35 55 Comparative 13 CeO₂ PMMA 5 1.0 0.01 90 10 example 14 CeO₂ PMMA 5 1.0 10 5 60

As can be seen from Table 6, it was learned that the slurries of embodiments 19 through 22 show very high polishing selectivity as they presented very high polishing speeds for the SIO₂ film and slow speeds for the Si₃N₄ film as the stopper film, thus achieving high planarity in Chemical Mechanical Polishing. In contrast to that, it was learned that comparative example 13, whose planarization additive's concentration was 0.01 wt %, shows that it has a very fast polishing speed for the SiO₂ film, but polishes through the Si₃N₄ film, which is the stopper film, as well, so that it has a shortcoming of not being able to achieve sufficient planarity. It was also learned that comparative example 14 whose planarization additive's concentration was 10 wt %, has high polishing selectivity and provides high planarity, but has a problem that its polishing speed for the SiO₂ film is very slow so that its process is very poor.

From the polishing tests of various embodiments, it is evident that the slurry for Chemical Mechanical Polishing, the Chemical Mechanical Polishing method using said slurry, and the method of producing electronic devices using said method as recited in the claims of the present invention have an excellent polishing capability for SiO₂ film, and provide effects that fully satisfy low scratch characteristics and polishing selectivity. Although the descriptions about the present embodiments were made concerning CMP of the STI method, the present invention can be applied to abradants for other processes where reduction of damages are required such as CMP in Inter Layer Dielectric (ILD) films.

INDUSTRIAL APPLICABILITY

The present invention can be applied to abradants used in processes where damage reduction is required such as CMP (Inter Layer Dielectric film CMP, etc., in addition to STI-CMP) for semiconductor devices, which are electronic devices. 

1. Slurry for Chemical Mechanical Polishing characterized in comprising abrasive grains (A) and water (B), wherein said abrasive grains (A) are composite particles coated with ceria particles consisting of organic host particles and ceria particles, zeta potential of said composite particles being a negative potential.
 2. Slurry for Chemical Mechanical Polishing as recited in claim 1 characterized in said organic host particles constituting said composite particles coated with ceria particles are organic host particles to which carboxyl groups and sulfonyl groups are introduced.
 3. Slurry for Chemical Mechanical Polishing characterized in comprising abrasive grains (A) and water (B), wherein said abrasive grains (A) are composite particles coated with ceria particles consisting of ceria particles and poly(methylmethacrylate) particles to which carboxyl groups are introduced.
 4. Slurry for Chemical Mechanical Polishing as recited in claim 3 characterized in said abrasive particles (A) being composite particles coated with ceria particles having a surface layer produced by fusion locally and intermittently applying pressure and shear force to mixed fine particles consisting of ceria particles and poly(methylmethacrylate) particles to which carboxyl groups are introduced.
 5. Slurry for Chemical Mechanical Polishing as recited in claim 3 characterized in the concentration of said abrasive particles (A) relative to said water (B) being in ratios of 0.2 to 10 weight percentage.
 6. Slurry for Chemical Mechanical Polishing as recited in claim 3 characterized in said abrasive particles (A) being composite particles having average particles diameters of 0.3 to 10 μm.
 7. Slurry for Chemical Mechanical Polishing comprising abrasive grains (A), water (B) and a planarization additive (C) characterized in said abrasive grains (A) being composite particles coated with ceria particles consisting of organic host particles and ceria particles, while zeta potential of said composite particles being a negative potential.
 8. Slurry for Chemical Mechanical Polishing as recited in claim 7 characterized in said organic host particles constituting said composite particles coated with ceria particles being organic host particles to which carboxyl groups and sulfonyl groups are introduced.
 9. Slurry for Chemical Mechanical Polishing comprising abrasive grains (A), water (B) and a planarization additive (C) characterized in said abrasive grains (A) being composite particles coated with ceria particles consisting of ceria particles and poly(methylmethacrylate) particles to which carboxyl groups are introduced.
 10. Slurry for Chemical Mechanical Polishing as recited in claim 9 characterized in said composite particles coated with ceria particles being composite particles coated with ceria particles having a surface layer produced by fusion locally and intermittently applying pressure and shear force to mixed fine particles consisting of ceria particles and poly(methylmethacrylate) particles to which carboxyl groups are introduced.
 11. Slurry for Chemical Mechanical Polishing as recited in claim 9 characterized in the concentration of said abrasive particles (A) relative to said water (B) being in ratios of 0.2 to 10 weight percentage.
 12. Slurry for Chemical Mechanical Polishing as recited in claim 9 characterized in said abrasive particles (A) being composite particles having average particles diameters of 0.3 to 10 μm.
 13. Slurry for Chemical Mechanical Polishing as recited in claim 9 characterized in the concentration of said planarization additive (C) relative to said water (B) being in ratios of 0.05 to 5 weight percentage.
 14. Slurry for Chemical Mechanical Polishing as recited in claim 9 characterized in said planarization additive (C) being poly(methyl)acrylic acid ammonium salt.
 15. A Chemical Mechanical Polishing method using slurry for Chemical Mechanical Polishing comprising abrasive grains (A) and water (B) characterized in said abrasive grains (A) being composite particles coated with ceria particles consisting of organic host particles and ceria particles, and causing a workpiece to be polished by being in contact with the slurry for Chemical Mechanical Polishing comprising composite particles, wherein zeta potential of said composite particles being a negative potential.
 16. A Chemical Mechanical Polishing method as recited in claim 15 characterized in causing a workpiece to be polished by being in contact with the slurry for Chemical Mechanical Polishing, wherein said organic host particles constituting said composite particles coated with ceria particles being organic host composite particles to which carboxyl groups and sulfonyl groups are introduced.
 17. A Chemical Mechanical Polishing method characterized in causing a workpiece to be in contact with and polished by slurry for Chemical Mechanical Polishing, said slurry for Chemical Mechanical Polishing comprising abrasive grains (A) and water (B), wherein said abrasive grains (A) being composite particles coated with ceria particles consisting of ceria particles and poly(methylmethacrylate) particles to which carboxyl groups are introduced.
 18. A Chemical Mechanical Polishing method using slurry for Chemical Mechanical Polishing comprising abrasive grains (A), water (B) and planarization additives (C) characterized in said abrasive grains (A) being composite particles coated with ceria particles consisting of organic host particles and ceria particles, wherein zeta potential of said composite particles being a negative potential.
 19. A Chemical Mechanical Polishing method as recited in claim 18 characterized in causing a workpiece to be polished by being in contact with the slurry for Chemical Mechanical Polishing, wherein said organic host particles constituting said composite particles coated with ceria particles being organic host composite particles to which carboxyl groups and sulfonyl groups are introduced.
 20. A Chemical Mechanical Polishing method characterized in causing a workpiece to be polished by being in contact with slurry for Chemical Mechanical Polishing comprising abrasive grains (A), water (B) and planarization additives (C), wherein said abrasive grains (A) are composite particles coated with ceria particles consisting of ceria particles and poly(methylmethacrylate) particles to which carboxyl groups are introduced.
 21. A method of producing an electronic device characterized in including a process of causing a workpiece to be polished by being in contact with slurry for Chemical Mechanical Polishing comprising abrasive grains (A) and water (B), wherein said abrasive grains (A) being composite particles coated with ceria particles consisting of organic host particles and ceria particles, and zeta potential of said composite particles being a negative potential.
 22. A method of producing an electronic device as recited in claim 21 characterized in including a process of causing a workpiece to be polished by being in contact with slurry for Chemical Mechanical Polishing, wherein said organic host particles constituting said composite particles coated with ceria particles being organic host composite particles to which carboxyl groups and sulfonyl groups are introduced.
 23. A method of producing an electronic device characterized in including a process of causing a workpiece to be polished by being in contact with slurry for Chemical Mechanical Polishing comprising abrasive grains (A) and water (B), wherein said abrasive grains (A) are composite particles coated with ceria particles consisting of ceria particles and poly(methylmethacrylate) particles to which carboxyl groups are introduced.
 24. A method of producing an electronic device characterized in including a process of causing a workpiece to be polished by being in contact with slurry for Chemical Mechanical Polishing abrasive grains (A), water (B) and planarization additives (C) characterized in said abrasive grains (A) being composite particles coated with ceria particles consisting of organic host particles and ceria particles, while zeta potential of said composite particles being a negative potential.
 25. A method of producing an electronic device as recited in claim 24 characterized in including a process of causing a workpiece to be polished by being in contact with slurry for Chemical Mechanical Polishing, wherein said organic host particles constituting said composite particles coated with ceria particles being organic host composite particles to which carboxyl groups and sulfonyl groups are introduced.
 26. A method of producing an electronic device characterized in causing a workpiece to be polished by being in contact with slurry for Chemical Mechanical Polishing comprising abrasive grains (A), water (B) and planarization additives (C), wherein said abrasive grains (A) are composite particles coated with ceria particles consisting of ceria particles and poly(methylmethacrylate) particles to which carboxyl groups are introduced. 